In September 2015 the Marine Corps released a study comparing the performance of gender-integrated and male-only infantry units in simulated combat. The all-male teams greatly outperformed the integrated teams, whether on shooting, surmounting obstacles or evacuating casualties. Female Marines were injured at more than six times the rate of men during preliminary training—unsurprising, since men’s higher testosterone levels produce stronger bones and muscles. Even the fittest women (which the study participants were) must work at maximal physical capacity when carrying a 100-pound pack or repeatedly loading heavy shells into a cannon.
